176 THE BLOOD. 



of leucocytes to the circulating blood does not increase its coagulability, 

 but the contrary; and, moreover, peptone plasma contains many 

 leucocytes. 1 These several facts were explained by Wooldridge by 

 the supposition that coagulation is produced or prevented in the 

 absence of leucocytes by the action of one substance in the plasma upon 

 another, or in the presence of leucocytes by the action of a substance 

 within the plasma upon these cells, or material yielded by them ; the 

 kind of interaction being different under different circumstances, and 

 producing, respectively, the phase of incoagulability or coagulation 

 (negative or positive phase) according to such circumstances. All such 

 substances, which by their interaction tended to produce fibrin, were 

 termed by Wooldridge " fibrinogens " ; but the progress of research has 

 since rendered it probable that WooMridge's " A-fibrinogen " obtained 

 from plasma, his " serum fibrinogen " obtained from dog's serum, and 

 the " tissue fibrinogens," which he obtained from various organs, all 

 owe their action to the nucleo-proteid which they contain. Translating, 

 then, the phraseology employed by Wooldridge, the alterations in 

 blood plasma, which come under the various conditions above noticed, are 

 due to the interaction of nucleo-proteids and fibrinogen. And it would 

 appear that, when in the interaction the nucleo-proteids are present in 

 relatively small amount, the negative phase is the result; when in 

 large amount, the positive phase. Also that, when added to the 

 circulating blood, leucocytes yield but little of their nucleo-proteid to 

 plasma, and hence a negative phase is the result : but, 011 the other 

 hand, when added to plasma in vitro, a larger amount is yielded, and 

 coagulation results. A remarkable observation, and one very difficult to 

 explain, is the fact that, if the negative phase is once established by the 

 intravascular injection of a small amount of nucleo-proteid, artificial 

 colloid, or snake venom, a large excess of the same will then not only 

 fail to produce the positive phase, but will even strengthen the negative 

 phase. It is, therefore, only the initial change which is influenced by 

 the relative amounts of interacting material ; and, when once this change 

 is established, it does not again become modified. 



Wright's experiments. Wooldridge further found that under some cir- 

 cumstances the amount of fibrin produced was dependent upon the amount 

 of tissue fibrinogen or A-fibrinogen (nucleo-proteid) added to plasma. He 

 therefore came to the conclusion, since the extent of action was not in all 

 cases independent of the amount of these substances, that the action could 

 not be looked upon as that of a ferment, although under some cir- 

 cumstances the extent of action did appear to be independent of the 

 amount of these substances. Wooldridge offered no explanation of the 

 different effects obtained with large and small doses respectively, his 

 work upon the subject having been cut short by his untimely death. 

 It has, however, been continued on the same lines by Wright, 2 who, 

 whilst confirming most of Wooldridge's observations, has added 

 materially to our knowledge of the conditions under which " tissue 

 fibrinogen " or nucleo-proteids produce the negative and positive phase 

 of coagulability. Wright states that the extracts of glands containing 



1 Wright found, however, that the number of leucocytes in peptone blood was extremely 

 reduced, much move so than is the case in oxalate or magnesium-sulphate blood, and that 

 it contains a correspondingly larger amount of nucleo-albumins, Proc. Roy. Soc. London, 

 10th Feb. 1893. 



2 Proc. Roy. Irish Acad., Dublin, 1891, 3rd series, vol. ii. p. 117. 



